/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the License);
 * you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.alibaba.polardbx.optimizer.core.rel.dml.util;

import java.util.Arrays;
import java.util.List;

public class RexHandlerChain<C extends RexHandlerCall> {
    public enum ChainState {
        CONTINUE, STOP;
    }

    private final List<RexHandler<C>> chain;

    protected RexHandlerChain(List<RexHandler<C>> chain) {
        this.chain = chain;
    }

    @SuppressWarnings("unchecked")
    public RexHandlerCall process(C call) {
        C currentCall = (C) call.copy();

        for (RexHandler<C> handler : chain) {
            if (handler.matches(currentCall)) {
                final ChainState state = handler.handle(currentCall);

                if (state == ChainState.STOP) {
                    break;
                }

                currentCall = (C) currentCall.copy(currentCall.getResult(), null);
            }
        }

        return currentCall.copy(call.getRex(), currentCall.getResult());
    }

    public boolean test(C call) {
        for (RexHandler<C> handler : chain) {
            if (handler.matches(call)) {
                return true;
            }
        }

        return false;
    }

    public static <C extends RexHandlerCall> RexHandlerChain<C> create(
        List<RexHandler<C>> handlers) {
        return new RexHandlerChain<>(handlers);
    }

    @SafeVarargs
    public static <C extends RexHandlerCall> RexHandlerChain<C> create(
        RexHandler<C>... handlers) {
        return new RexHandlerChain<>(Arrays.asList(handlers));
    }
}
